The present invention relates to a laser generating apparatus which excites a solid state lasing medium by means of laser light, and thereby outputs laser light.
Examples of technology for the excitation of a solid state lasing medium (thus placing this medium in a laser oscillating state) were disclosed in Japanese Patent Application, First Publication, Laid-Open No. 1-107588 (Solid State Laser Apparatus); and Japanese Patent Application, First Publication, Laid-Open No. 1-205484 (Laser Apparatus).
In the technology disclosed in Japanese Patent Application, First Publication, Laid-Open No. 1-107588, a plurality of excitation light sources comprising semiconductor lasers are disposed circumferentially around a lasing medium comprising a solid crystal, and energy conversion efficiency is increased by outputting excitation light into the radial center of the lasing medium; in the technology disclosed in Japanese Patent Application, First Publication, Laid-Open No. 1-205484, a plurality of gaps for the input of excitation light is formed in a portion of a reflecting surface surrounding the outer circumference of a solid crystal lasing medium, the excitation light is further confined by increasing the area of the reflecting surface, and the energy conversion efficiency is thereby increased.
However, in both of these technologies, excitation light sources are disposed around the cylindrical surface of a lasing medium, so that the total surface area of the reflective surface around the lasing medium is reduced by that area which is occupied by the excitation light sources themselves, and therefore the places at which the excitation light is inputted are incapable of performing reflection of the excitation light, so that there is a limit to the increase in energy conversion efficiency, and furthermore, there is a limit in obtaining a good distribution of the excitation of the lasing medium having high intensity at the central axis thereof.